From U.S. Pat. No. 4,405,680 roofing singles are known having improved low temperature flexibility comprising a flexibilized mat prepared by impregnating a glass fiber web with the blend of an unblown asphalt (or bitumen) and a monoalkenyl arene-conjugated diene block copolymer, wherein the flexibilized mat is coated with a blend of an airblown bitumen and a filler.
From U.S. Pat. No. 5,308,676 a torchable roll roofing membrane is known which comprises a reinforcing mat which is saturated and coated with bituminous composition comprising a bituminous component and, optionally, an unhydrogenated block copolymer of a monoalkenyl aromatic hydrocarbon and a conjugated diolefin, and coated onto one surface, a bituminous composition comprising a bituminous component and a hydrogenated block copolymer of a monoalkenyl aromatic hydrocarbon and a conjugated diolefin.
From U.S. Pat. No. 5,051,457 a composition is known for use in roll roofing membrane applications which comprises (a) from about 93 to about 87 parts per hundred of a bituminous component having a penetration of less than about 125 dmm (decamilimeters) at 25° C. and (b) from about 7 to about 13 parts per hundred of a hydrogenated block copolymer of a monoalkenyl aromatic hydrocarbon and a conjugated diolefin having a contour arm molecular weight before hydrogenation of from about 105,000 to about 140,000 and a polystyrene content of from about 25% to about 37%.
From U.S. Pat. No. 5,130,354 a bituminous composition is known comprising a bituminous component and a silane functionalized polymer or an acid functionalized polymer of a conjugated diolefin, which may be used to saturate and coat the reinforcing mat of roll roofing membranes.
From U.S. Pat. No. 4,904,713 a bituminous composition is known comprising a bitumen, an elastomeric, optionally hydrogenated, block copolymer containing at least two alkenyl arene blocks A and at least one conjugated diene block B, and a polymer of a monoalkenyl arene of which polymer the number average molecular weight is in the range of 0.25 to 2 times the number average molecular weight of the polymeric blocks A. The bituminous composition has excellent elasticity, flexibility and adhesion properties, which render it especially suitable for use in roofing coatings.
From U.S. Pat. No. 5,447,775 a bituminous roofing composition is known that is especially useful to coat and/or saturate a roll roofing membrane. The composition comprises from 2 to 10 percent by weight based on block copolymer plus bitumen, of a block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene, from 25 to 300 parts by weight per hundred parts of said block copolymer of an end block compatible resin which has a softening point above 100° C., and the balance being a bituminous material.
From U.S. Pat. No. 5,718,752 a bituminous composition is known comprising a bituminous component and a radial block copolymer of styrene and butadiene which has the generalized formula:(B1—S—B2)n—Ywherein B1 is a block of polybutadiene having a weight average molecular weight of from 2,000 to 8,000, S is a block of polystyrene having a weight average molecular weight of 10,000 to 30,000, B2 is a block of polybutadiene having a weight average molecular weight of from 40,000 to 100,000, Y is a multifunctional coupling agent, and n is an integer from 3 to 6. This polymer modified bituminous position has improved processing viscosity and hence improved processability.
From U.S. Pat. No. 6,133,350 an oil-free bituminous composition is known which comprises from 80 to 98% by weight of a bituminous component, and from 2 to 20% by weight of an oil-free compound which comprises from 20 to 90% by weight of a block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene optionally hydrogenated, from 10 to 70% by weight of a low viscosity amorphous polyolefin, and from 0.1 to 20% by weight of carbon black. The composition may be used for the production of single ply membranes as widely used in the roofing industry.
From U.S. Pat. No. 5,854,335 a bituminous composition is known which comprises a bituminous component and a block copolymer of a conjugated diene and a monovinylaromatic hydrocarbon, wherein the block copolymer has a vinyl content of at least 25% by weight based on the total diene content and a diblock content of 25 wt. % or less, whereas the diblock has an apparent molecular weight which is in the range of from 100,000 to 170,000. This composition is of use particularly in roofing applications.
From Canadian patent No. 1,225,177 a bituminous composition having improved stability is known comprising (a) 100-30 wt. % of a mixture of (1) 40-99.8 wt. % of a bituminous component having a penetration of less than 800 (decamilimeter) at 25° C., (2) 0.1-50 wt. % of a block copolymer having at least one thermoplastic monoalkenyl arene polymer block A and at least one elastomeric conjugated diene block B, and (3) 0.1-10.0 wt. % of a polystyrene-poly(ethylene-propylene) diblock copolymer, and (b) 0-70 wt. % of a filler.
It is thus known to use the above referenced block copolymers (generally referred to as styrenic block copolymers) in bituminous compositions and in particular in bituminous compositions for roofing applications.
In the roofing industry, modified bitumen membranes are generally applied by torching with open flame, or by mopping with hot bitumen or asphalt. Both methods can ensure a strong and watertight seam of overlapping membranes. However, mopping creates health and odour concerns while torching carries the risk of fire. Use of cold-applied solvent-based adhesives is growing rapidly but there are still limitations associated with VOC issues and long curing times.
A growing demand for self-adhesive roofing membranes, driven in part by insurance companies and legislation to increase the safety of the installation workers, stimulates the use of self-adhesive, bituminous roofing membranes, that can be applied without torching, hot bitumen or solvent-based cold adhesives.
Although there are regional differences, premium self-adhesive roofing compositions are generally composed of multiple components: bitumen/asphalt, a mixture of various styrenic block copolymers, (e.g., SBS, SIS and SB), tackifying resin, naphthenic oil, oxidised bitumen and filler. What components are used and in what amount is determined partly by the requirements for the final product. However, most importantly, this is strongly influenced by the kind of bitumen or asphalt that is used. In addition to the same high temperature performance requirements of conventional membranes, self-adhesive compounds have the additional requirement of being tacky at the lowest application temperature. This more stringent requirement of performance over a wide temperature range usually necessitates more complex compositions.
The three most important characteristics required in self-adhesive compositions are: flow resistance, low temperature tack and resistance to dis-bonding. The first two are primarily rheology requirements, while the latter is characterised by adhesive and cohesive strength. Rheological models exist for standard non-bituminous compounds, but with asphalt being the major component, the models no longer apply. Recent developments focus on simplifying the compositions and thereby easing its manufacture as well as that of the self-adhesive felt.
Surprisingly, a self-adhesive bituminous composition has been developed that satisfies the conflicting requirements.